heres how to find the derivative of sin(-1)x. first the arc length of part of the circle in terms of x is squareroot of int{1+(-x/(squareroot(1-x^2))^2} which is the basic formula for the distance of part of the circle in terms of x. so simplifying this, you come up with (1-x^2)/(1-x^2)+x^2/(1-x^2) and this gives 1/(1-x^2) => int 1/(1-x^2) when integrated this it will give you the distance, which will be expressed in radians of part of the circle. because the arc length of the circle is directly related to the length of the circle, then it should be sin(-1)x. cause this will give arc length (radian measure) in terms of x. or something along those lines. im trying...